Abstract :
[en] Asymptomatic and pauci-symptomatic cases contribute to underestimating the prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. Moreover, we have few studies available on the longitudinal follow-up of SARS-CoV-2 antibodies after natural infection. We tested staff members of a Belgian tertiary academic hospital for SARS-CoV-2 IgG, IgM, and IgA antibodies. We analyzed the evolution of IgM and IgG after 6 weeks, and the persistence of IgG after 3 and 10 months. At the first evaluation, 409/3776 (10.8%) participants had a positive SARS-CoV-2 serology. Among initially seropositive participants who completed phases 2 and 3, IgM were still detected after 6 weeks in 53.1% and IgG persisted at 12 weeks in 82.0% (97.5% of those with more than borderline titers). IgG levels were higher and increased over time in symptomatic but were lower and stable in asymptomatic participants. After 10 months, 88.5% of participants had sustained IgG levels (97.0% of those with more than borderline titers).
Funding text :
This study was supported by the Wallonia Region of Belgium (Convention n° 2010075) and the Leon Fredericq Foundation (University of Liège).The ZenTech company kindly provided immunochromatographic assays for IgM and IgG detection on serum samples. The authors thank Michel Georges (VetD, PhD, Director of the GIGA Institute, University of Li?ge) for his support and helpful comments on the study design and the manuscript. We also thank Denis Deriaz (MD, Department of Biostatistics and Medico-economic Information, CHU of Li?ge) for his contribution to the database content before statistical analysis and his comments on the manuscript. The help of Eric Haubruge, Advisor to the Rector of the University of Li?ge, for obtaining the support of the Wallonia Region was really appreciated. We also thank all the persons who have considerably contributed to this study, in particular: Noemi Javaux who organized all the logistical aspects of the study on 5 different sites; Laurent Debra, Michel Raze and Isabelle Simon and their staff who consolidated the IT aspects of this organization; Alain Didderen and his staff who handled appointments with study participants; Ann Robin and her team of more than 15 data managers from the Division of Hematology and other departments of the hospital who managed inclusion of participants in the study; Jocelyne Kariger, Stephanie Leroy and their respective staffs, who verified and encoded all questionnaires; all the nurses involved in collecting blood for the biobanking effort and the serology study; the staff of the Bioth?que Hospitalo-Universitaire de Li?ge (BHUL) and numerous volunteers who handled the biological samples for biobanking and serology; Fran?oise Toussaint, Head Technician of the Laboratory of Infectious Serology and her team, who performed all the serological tests.
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